The objective of this study—to determine whether interaction between the upper cervical dorsal roots and the trigeminal system occurs—was approached by investigation of single-unit responses to trigeminal and cervical-root volleys.
A large volume of literature is available on single-unit responses in the lumbar enlargement; in particular, the ventral horn cells have been the subject of most of these reports. Cells in the dorsal horn lend themselves less satisfactorily to such studies, mostly because of their reduced size, exceptions being some large neurons in lamina I of Rexed (old terminology, N. megnocellularis pericornualis) and lamina IV (in the old terminology, the N. magnocellularis centralis is contained within lamina IV).
As a result, the studies on their properties are still relatively few.2,9,14-16
Interneurons in other regions have been the subject of a number of reports.1,3,5,6
Material and Methods
Adult cats weighing between 4 and 10 pounds were used. In the